In most low- and middle-income countries (LMICs), traffic crash victims are transported from the crash scene to a hospital by bystanders and passing vehicles. Organized emergency medical systems (EMS) with ambulances and trained providers are costly and unlikely to be deployed in many LMICs for the foreseeable future. Therefore, the World Health Organization recommends that lay first responders be trained to provide basic aid at a crash scene and rapidly transfer victims to a hospital. This raises the question: Would a dispatcher-coordinated layperson EMS improve crash outcomes in LMICs? The ongoing revolution in smartphone technologies has already transformed urban transport in many LMICs. A smartphone application, PoochO, developed by our team is being used by residents of New Delhi, India, to request a taxi, track its arrival in real time, and estimate the quickest route in traffic. An EMS built around a large fleet of coordinated taxis can potentially provide faster crash response than an ambulance system. Therefore, this project aims to develop the concept of a taxi-based, dispatcher-controlled, layperson EMS for use in LMICs by addressing a range of social, legal, and technical questions. This project will have three specific aims: 1. Establish the feasibility of implementing a taxi-based dispatcher-coordinated EMS in LMICs. We will interview key informants, including taxi drivers, doctors, nurses, lawyers, police personnel, and other stakeholders, to understand crash scene processes and how the regulatory and legal landscape in India affect a purpose-built layperson EMS. We will design the systems architecture of the EMS, develop the core smartphone application by extending PoochO, and conduct a field trial of the application through dry runs. 2. Develop the technical specifications for a taxi-based EMS in New Delhi through mathematical simulation. We will develop a computational model to assess how a city's urban transport network and typical congestion patterns affect performance of a taxi-based EMS. For model inputs, we will collect data from New Delhi about the geospatial and temporal distribution of crashes, hospitals, taxis, and traffic congestion. Using parametric studies, we will answer the question: Given the distribution of taxis in New Delhi, what level of taxi participation is needed to provide quicker hospital transfer than a realistic implementation of ambulance-based EMS? 3. Build the multidisciplinary partnerships needed for implementation of taxi-based EMS in LMICs. We will build a multidisciplinary (engineering, health, transport) and cross-sectoral (academic, corporate) team in India facilitated through scholar exchanges and substantial physical and virtual interactions. We will organize a domestic (India) and an international workshop to disseminate findings, understand concerns in other settings, and build a global research network focused on layperson EMS. Thus, this project will establish the logistical feasibility, technical parameters, and multidisciplinary partnerships needed for a real-world trial of a taxi-based EMS in India or another LMIC setting.